Drafting instrument.



G. H. LITTLE.

DRAPTING INSTRUMENT.

APPLICATION FILED JULY 2.1902.

Patented Dec. 16, 1913.

2 SHEETS-SHEET 1.

G. H. LITTLE.

DEAFTING INSTRUMENT.

APPLICATION rum JULY 2, 19oz.

Patented Dec. 16, 1913.

2 BHEETS'-SHEET 2.

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CHARLES H. LITTLE, F CLEVELAND, OHIO.

DRAFTIN G INSTRUMENT.

Specification of Letters Patent.

- Patented Dec. 16, 1913.

Application filed July 2, 1902. Serial No. 114,115.

To all whom it may concern:

Be it known that 1, CHARLES H. LITTLE, a citizen of the United States, and resident of Cleveland, county of Cuyahoga, and State of Ohio, have invented certain new and useful Improvements in Drafting Instruments, of which the following is a specification, and which are illustrated in the accompanying drawings, forming a part thereof.

This invention relates to drafting instruments for drawing parallel lines, and particularly to certain improvements in an instrument of this character which forms the subject of an application for patent filed by me September 11th, 1901, and numbered serially 75,004. That invention consists, ,generally, as shown herein, of a jointed arm, each member of which is in the form of a parallelogram having the several sides thereof pivotally united, the arm being provided at one end with an anchor block for attachment to a drafting board and at the other with a protractor or such form of drafting tool as it may be desired to use.

The present invention has particular ref- ,erence to certain details of construction, and.

consists of the combination and arrangement of parts hereinafter particularly described, specifically designated in the claims, and which are illustrated in .the accompanying drawings, in which- Figure 1 is a detail'plan view of a drawing board and of the instrument applied thereto; Fig. 2 is a detail plan view of .a ruler for use in connection with the instrument; Fig. 3 is a detail plan viewof the protractor, the hand piece or knob being removed; Fig. 4 is a detail sectional view on the line W-X of Fig. 3, the hand piece or knob being shown; Fig. 5 is a detail section on the line ST of'Fig. 1; Fig. 6 is a detail side elevation of a portion of the protractor; Fig. 7 is a detail side elevation of the anchor block; Fig. 8 is a detail section on the line QB of Fig. .3; Fig. 9 is a detail section on the line U-V of Fig. 1 showing the chuck forming a part of the protractor for receiving the chuck block of the ruler;

Fig. 10 is a detail section on the same line,

showing the ruler with its chuck bloclc for engaging the chuck shown in F'g. 9; and Fig. 11 relates to a modification of the construction illustrated in Fig. 4.

A portion of a drawing board is represented at 11, and to the upper left hand corner of this drawing board the anchor block of the drafting instrument is secured. The base plate of'the anchor block is represeated at 12 and as being secured to the drawing board by means of screws. The upper member or plate 13 of the anchor block is secured to the base plate thereof by means of pivot screws 14, 14, setting through lugs 15, 15, depending from the plate 13 and overlapping the side edges of the base plate 12, the ends of which are sockcted to receive the screws 14. Lock nuts 16 may be mounted upon the pivot screws 14.

The first section of the jointed arm is comprised of the plate 13, a pair of parallel rods 17 pivotally secured thereto, and the ring 18 to which the outer ends of the rods 17 are pivotally attached. The second member of the jointed arm comprises the ring 18, a pair of parallel rods 19 pivotally secured thereto, and a cross-bar 20 to which the outerends of the rods 19 are pivotally attached; and the points of attachment of the side bars of the arm members to the ring 18 are so arranged that lines passing through each pair of pivots intersect. Extreme accuracy of construction-is of vital importance, particularly inthe jointed arm, as any errors therein are greatly accentuated at the outer end of the instrument. It is practically impossible to uniformly secure accuracy in loeating all of the pivots of the jointed arm, due to variations in tools, errors in measure ments, etc. For this reasomthe intermediate member is given the annular or ring-form which admits of. suflicient bending or shaping after the parts are assembled to bring the several pivots by which the rods are attached, to the position necessary to secure exact parallelism of the members of each pair of bars.

The cross-bar 20 forms the anchorage for the protractor, which consists of a base plate 21 securely attached to the bar 20, preferably b means of rivets, and a rotatable plate 22 a ve and pivotally united to the plate 21 by means of a pin or post 23 which is preferabl} in fixed relation to the plate 21 and provided with a sleeve 23 having a shoulder 24 against which the plate 22 bears, a spring 37 reacting between a nut at the top of the pin and the sleeve to press the shoulder 24 against the plate 22.

A pair of ruler attaching bars 24, 25, in perpendicular relation, are secured to the plate 22. In the present construction each of these bars is provided with a longitudi nally dove-tailed channel, which is slightly tapering toward its inner end, for receiving the chuck block\26, of corresponding form, secured to the ruler 27', 28 or 29 to be used in connection with the instrument, so that the ruler may be readily secured to or detached from the protractor.

In order to secure nicety of adjustment the chuck block is secured to the ruler by means of two screws, and the aperture at one end of the block, as 26 is elongated transversely as to the block, as plainly shown in Fig. 2, so that after the screw at the opposite end has been set the ruler may be turned with relation to the chuck block before the screw at the slotted end is turned down tightly.

A graduated scale, 30, is formed on the plate 22 and cooperates with a scale mark 31 formed on the cross-bar 20. A clamping device is provided for locking the two plates 21 and 22 in the angular relation to which they may be adjusted, and as shown this consists of a screw bolt 32, having in its head a lateral slot for loosely receiving the plate 21, the screw extending upwardly through the chuck. bar 25 and having applied to its upper end a thumb nut 33.

F or convenience in more quickly securing the upper plate 22 at any one of the angles most commonly used in drafting operations, the plate 21 is provided, as in the former construction, with a number of apertures, as indicated Wlthk dotted lines at 34, into which may fall a bolt 35, playing in a sleeve 36, carried by the chuck-bar 24. The bolt 35 is pressed downwardly b means of the spring 37, heretoforereferre to, which may be conveniently anchored to the pivot pin 23, as shown, its outer end being upturned to form a thumb piece by which the bolt may be raised. lhe upper end of the sleeve 36 is .shown as cam shaped, see Fig. 6, and a pin 38, projecting laterally from the bolt '35, serves the purpose of a stop to prevent the bolt from entering the apertures 34 when it is turned so as to ride upon the more elevated portion of the cam. To facilitate the entering of the bolt 35 in the apertures 34 it is provided witha tapering end.

'As shown in Fig. 4 the ruler bar 24a: is secured to the plate 22 by the sleeves 23 and 36.

A T-headed screw 39 may be set in the chuck-bar 24: so that its head will overlap the plate 21, thereby strengthening the instrument and preventing distortion of the plates 21, 22 by careless handling. A handpiece or knob 40 is preferably mounted upon and secured to the plate 22 in any desired manner, entirely covering the pivot'23 and serving as a housing for the spring 37 and as means for controlling the entire instrument and for turning the protractor.

. mamas A thumb-screwed, sitting through the plate 13 forward of its pivot line, bears upon the upper face of the plate 12 so as to adjustably limit the downward movement of the ointed arm. By the use of this screw the arm may be elevated suiiiciently so that it will clear the drafting board. It is im-. portant, however, tnat the rulers carried by the arm should be capable of lying firmly upon the drafting board, and to this end the rods 17 and 19 are preferably flattened and made of strong and elastic material, such as steel, so that the weight of the hand upon the knob 40 will flex them suflicient to bringthe rulers firmly to the board.

Instead of employing the spring 37 anchored to the pin 23 for pressing the bolt 35 into place, as shown in Fig. 4:, a leaf spring 37 (see Fig. 11) may be used and secured to the plate 22, such spring having an aperture through which the sleeve 23 passes. With this arrangement an expan sion spring 38, coiled about the pin 23, is employed in lieu of the spring 37 for pressing upon the sleeve 23*- in order to secure the plates 21 and 22 upon the pin 23.

By the use of the chuck form of attachment of the rulers to the drafting instrument a plurality of rulers may be used. The preliminary work may be drawn to a scale, thereby obviating the use ofan eraser, and if desired, after the drawing has been penoiled, the scales may be removed and the ruler, such as 29, substituted for use in connection with a ruling pen.

As shown'the attaching bars carried by the protractor are inclined at their outer ends toward the drafting board, so that as the protractor is pressed toward the board, either by its own weight or the weight of the hand of the user, the ruler is sure to come into contact with the board through its entire length.

too

It will be seen that the anchor block is recessed at its edge to receive the ends of the bars 17 which fit snugly within the recess, so that they are supported by the walls thereof, thus relieving their pivots from undue strain. By the use of this form of construction the arm will swing on its pivots more easily and with much less wear than would be the case if the pivots themselves were obliged to sustain the entire weight.

ll claim as my invention- 1. In a drafting instrument, in combination, an anchor block, a pair of parallel bars pivoted to the anchor block, asecond pair of parallel bars, a plate carried by the latter bars, an intermediate member to which the i which is provided with an inwardly tapering longitudinally dove-tailed channel, and a chuck plate of corresponding form removably seated in each channel and having secured thereto a ruler.

2. In a drafting instrument, in combination, a dplate, a pair of ruler-attaching members a justably mounted on the plate and each of which is provided with an inwardly tapering longitudinally dove-tailed channel, and a chuck plate oi corresponding form seated in each channel and having secured thereto a ruler.

In a drafting instrument, in combination, a plate, a pair of ruler-attaching members adj ustably secured to the plate and each of which is provided with an inwardly tapering longitudinally dove-tailed channel, and blocks of corresponding form engaging the channels and having rulers secured thereto, one of the said rulers being laterally adjustable with relation to the chuck plate secured thereto.

4. In a drafting instrument, in combination, an anchor block, a pair of parallel bars pivoted to the anchor block, a second pair of parallel bars, a plate secured to the latter bars and having a series of holes, an intermediate member to which ,the said sets of bars are pivoted in such manner that the angularity of the plate remains constant, a rotatable member mounted on the late, a pair of ruler-attaching bars secur to the rotatable member, a sleeve fixed'to the rotatable member and rovided with a shoulder, a spring-presse rotatable bolt sliding in the sleeve and adapted to engage the holes in the plate, and a pin pro'ecting from the bolt for engaging the shoulder.

5. In a drafting instrument, in combination, an anchor block, a air of parallel bars attached thereto, a crossead pivotally uniting the ends of the bars, a second pair of parallel bars pivotally attached to the crosshead, the lines of pivotal attachment of the two sets of bars intersecting, a head pivotally uniting the outer ends of the second set of bars, a ruler holder carried by the lastnamed head and having a dove-tailed tapering recess, and a ruler carrying a chuck plate complementary in form and size to the recess of the ruler holder.

6. In a drafting instrument, in combinati on, an anchor, a recessed plate united thereto by a horizontal pivot, a positive stop for limiting the downward movement oi the plate, and an arm swingingly mounted within the recess and having a bearing against the tcip and bottom thereof.

7. n a protractor, a pair of pivotally connected plates, one of such plates carrying rulers, one plate being provided with a concentrically arranged series of apertures, a sleeve carried by the other plate at the same radial distance from the pivot and opening through the said plate and having a shoulder at its other end, a tapering pin playing through said sleeve, and having at its upper end a lateral projection for engaging the shoulder of the sleeve.

8. In a drafting instrument, in combination, two pairs of arallel bars united by a common cross-Inem er to which the several bars are pivoted, such cross-member being annular in form.

9. In a drafting instrument, in combination, two pairs of parallel bars united by a common cross-member to which the several bars are pivoted, such cross-member being centrally provided with a relatively large aperture so that the shape of the member may be changed by bendin CHARLE H. LITTLE. Witnesses:

LOUISE L. GILLSON, E. M. KLATCHER. 

